Silicon doped metal oxides are potential materials for high-performance electrochemical energy storage because of the synergistic effect. In this work, Si/NiCo₂O₄ heterostructures have been successfully synthesized by a two-step solution-phase method. The characterizations demonstrate that the Si nanoslices dispersed uniformly in NiCo₂O_4. Serving as electrochemical electrode, the Si/NiCo₂O₄ heterostructures present high specific capacitance of 1972.1 F g⁻¹ at a current density of 2 A g⁻¹ and excellent reversibility with a cycling efficiency of 78% after 2000 cycles, which is approximately two times higher than that of NiCo₂O₄. The outstanding electrochemical performance is mainly attributed to the Si doping effect and synergistic effect between Si and NiCo₂O₄. This work suggests a way to design silicon doped electrode materials with enhanced performance for supercapacitors.